Calculating Volume by Rotating y = e^x * sin(x) Around the x-Axis

Click For Summary

Homework Help Overview

The discussion revolves around calculating the volume of a solid formed by rotating the function y = e^x * sin(x) around the x-axis over the interval [0, π]. Participants are exploring the appropriate integral setup for this volume calculation.

Discussion Character

  • Exploratory, Mathematical reasoning, Problem interpretation

Approaches and Questions Raised

  • The original poster attempts to set up the integral for volume using the formula involving π and the square of the function. They express uncertainty about their approach and seek hints for solving the integral. Some participants suggest transforming sin²(x) into a more manageable form to facilitate integration.

Discussion Status

Participants are actively engaging with the problem, offering hints and discussing different approaches to simplify the integral. There is a collaborative atmosphere as they explore various transformations and their implications for solving the integral.

Contextual Notes

Participants are working within the constraints of a homework assignment, which may limit the types of guidance they can provide. The original poster expresses difficulty with integration by parts, indicating a potential gap in their understanding of the method.

TSN79
Messages
422
Reaction score
0
I'm supposed to find the volume of the figure that appears by rotating the follwing around the x-axis:
[tex]y = e^x \cdot \sin (x) & x \in \left[ {0,\left. \pi \right]} \right.[/tex]
This means (I think) that the function needs to be to the second power and multiplied by Pi in an integral. So the integral becomes
[tex] \pi \int {e^{2x} \cdot \sin ^2 (x)dx} [/tex]
I need hints on how to solve this integral, I've tried integration by parts but not really gotten anywhere...am I on the right track?
 
Physics news on Phys.org
here is a hint, maybe change sin squared into something more friendly.
 
Last edited:
I tried to change it into 1-cos2x = 2(sinx)^2, but I didn't find it to make it any easier...was that what you thought about?
 
yes, change (sinx)^2 = 1/2 - (1/2)cos2x. multiply your e function through and you will have 2 integrals that can be solved. the integral with (e^2x)(1/2 cos 2x) is going to need parts twice.
 
Last edited:
I do believe you might be on to something there 1800bigk...thx!
 

Similar threads

  • · Replies 5 ·
Replies
5
Views
4K
Replies
3
Views
2K
Replies
7
Views
3K
Replies
3
Views
2K
Replies
4
Views
3K
  • · Replies 9 ·
Replies
9
Views
3K
Replies
5
Views
3K
Replies
2
Views
2K
Replies
2
Views
3K
  • · Replies 5 ·
Replies
5
Views
2K